This invention relates to a method and apparatus for processing photographic material. In particular the invention relates to a single use processor.
Conventional processing of photographic material requires the use of large tanks of processing solutions. Typically these processing tanks have volumes greater than three liters. Each tank contains a processing solution such as developer, bleach, fixing solution or washing solution. The material is transported through each tank in turn. There is a tendency for the solutions to carry over from one tank to another leading to pollution of the solutions. Conventional processing has several other drawbacks. The temperatures which can be utilized are limited and therefore the process is slow. The composition of the solutions must be stable over long time periods in the processing tanks. The processing apparatus is also very large due to the number of processing tanks. To overcome these problems low volume thin tanks were developed. Replenishment of these solutions is difficult to control. The low volume thin tanks reduced capacity to about one liter. An example of such a low volume thin tank is the Noritsu V30 film processor.
Low volume thin tanks currently operate in a state of dynamic equilibrium and process control is required.
It is desirable to reduce the volumes of low volume thin tanks further to that of the replenishment rate of the process (for a given length of film) or even lower. In order to do this volumes can be made small but the chemical content of such small volumes needs to increase greatly as we need to be able to develop Dmax in any area of the film and no exposure history is known. This requirement becomes prohibitive as the volume approaches that of the film gelatin swell. GB 9930140.0 discloses a method and apparatus for processing photographic material in which the low volume of applied solution can be reused by moving it about the film surface with a porous pad. This reduces the component requirement in any part of the film. The method disclosed in GB 9930140.0 relies on low volume and high physical agitation to replenish areas where the swollen gelatin is exhausted of developing agent or saturated in seasoning components. This method has become known as Dynamic Single Use (DSU). Problems with the pads arise due to pressure sensitivity lines and evaporation from the heated film. It is also not obvious how the pad would be operated in the field or cleaned and/or replaced.
The present invention solves these problems by maintaining the solution in a tank that can be heated, easily loaded and unloaded and is self cleaning if all of the process occurs in the same tank.
According to the present invention there is provided a method of processing photographic material comprising the steps of transporting the material to be processed into at least one tank containing a predetermined volume of processing solution and plunging a reciprocable member into the tank to thereby rapidly displace the solution through the narrow channels created between the tank and member and thus across the surface of the material.
The present invention further provides an apparatus for processing photographic material comprising at least one tank containing a predetermined volume of processing solution, an equivalent number of reciprocable members for plunging into each respective tank and means for transporting the material into and out of the at least one tank.
Preferably a plurality of reciprocable members are provided.
The invention overcomes the problems of the prior art. The processor is of low volume, provides high agitation and wets the whole film quickly. This avoids seasoning effects between opposite ends of the film.
Temperature control is easy at elevated temperatures and higher temperature solutions can be utilized than in conventional tanks. This enables more rapid processing. Unstable processing solutions can be used as only small volumes are required. These solutions can then be disposed of after use. If the process ends with a wash step the processor is self cleaning.